Both of these are ungated. Ken Rogoff's abstract gives a good sense of the review and response:
Jeffrey Hummel provides an extremely thoughtful and detailed review, which is welcome, even if there are a number of places where I don’t quite agree with his interpretations, emphasis, and analysis. For example, the notion that central banks already can use helicopter money to solve the zero bound, and that there is little need for negative interest-rate policy in the next deep financial crisis, is dubious. It is also important to stress that the book is about the whole world and not just the United States; there are good reasons why many other advanced economies may find it attractive to move away from the status quo on cash much more quickly than the United States will. Importantly, deciding how to move to a less-cash society should be looked at as a question of calibration, not an all-or-nothing proposition, and not something that needs to be done quickly.